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Teresa Binstock
Researcher in Developmental & Behavioral Neuroanatomy
June 07, 2009
Introduction: A recently published study links intestinal inflammation to an increased tendency for excessive excitation within the CNS (17). This very important study is free online. Note that the cytokine Tumor Necrosis Factor alpha (TNFa) is etiologically significant in this gut-brain connection and that TNFa has been found to be atypical in many autistic children. Additional relevance of the relationship between peripheral inflammation and CNS excitability (17) derives from the facts (a) that casein induces TNFa in children with hypersensitivity to milk, and (b) the gluten-free and casein-free diets have been found to lower TNFa.
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A newly published study reports that a gluten free diet (GFd) alters intestinal flora and cytokines profiles in healthy human adults. Whereas a person's "gut bugs" are important, so to is having an appropriate array of cytokines. In the GFd study, flora profiles were altered and cytokine expression was changed. Indeed, "TNF-alpha, interferon-gamma, IL-10 and IL-8 production by PBMC stimulated with faecal samples was also reduced... after the [GF] diet." (1)
Relevance to autism derives from several considerations. For instance, many parents of autistic children try a gluten-free (GF) and/or casein-free (CF) diet, and results are generally positive. Among >2500 parents who reported effects of GF and/or CF diet, 3% noticed negative effects, 31% noticed no change, and 66% reported improvements. Importantly, the ratio of improved to got-worse ratio was 19 to 1 (2). Thus, the new findings about gluten-free diets in health adults prompts a question. Why might a GF-free diet help some and perhaps many autistic children? Let's keep in mind the fact that GFd reduced TNFa.
At least 14 studies describe atypical TNFa in autistic subjects (eg 3), most of whom aren't healthy adult humans (1).
Studies of TNFa in autism:
Brain (3)
CSF (4, 6)
Periphery (7,8,12)
Gastrointestinal (5,9)
Gastrointestinal & food responses (7-9,11)
LPS challenge (8,13)
Negative findings, periphery w/o LPS-challenge (10,16)
Viral mouse model (14)
Skewed immunity to PBDE, BDE-47 (15)
Given these TNFa findings in autism, the finding that a gluten-free diet can lower TNFa has relevance enhanced by an important new study, which is free online. Riazi et al reported that "Microglial activation and TNFalpha production mediate altered CNS excitability following peripheral inflammation." (17) In other words, intestinal inflammation contributed to the induction of microglial activation and to increases in CNS excitability. Furthermore, increased levels of TNFa in the brain were etiologically significant to excitability. The findings by Riazi and colleagues suggest a mechanism by which gluten-free and casein-free diets might be beneficial for substantial subgroups of autistic children.
i) Gliadin and gluten have long been known to induce TNFa (eg, 18-20).
ii) Pathologies labeled as celiac disease are realized to have a wider range of symptomatology than were specified by the original criteria (21-27).
iii) Casein increases TNFa in children hypersensitive to milk (31-32, see also 33).
Speculation: The finding that GF diet alters intestinal microbiota profiles in healthy adults may need be set aside for some children with intestinal inflammation and elevated TNFa, especially for children who respond well to a GF and/or a CF diet. Many studies document skewed TNFa (previous cites) and/or intestinal inflammation in subgroups of autistic children (28-30). Lowering TNFa (even somewhat) via GF or CF diet may be beneficial for some of those children. Thus we ask, which is the more serious pathology - skewed microbiota (1) or elevated TNFa (3), especially given the finding that intestinal inflammation alters CNS excitability via increased TNFa (17)?
Since Riazi et al's finding that intestinal inflammation alters in-brain TNFa and CNS excitability emerged from a rat study (17), the results do not necessarily apply to children with autism. Nonetheless, there is consistency between the Riazi et al findings and parent descriptions of GF and CF diets (2). Furthermore, the many descriptions of altered TNFa in autistic subgroups (3-9,11-15) suggest that the GF or CF diet's alteration of TNFa, in the very least, may be a contributing factor in the mechanism by which the GF or CF diet helps some children (2).
References:
1: Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects.
De Palma G et al. Br J Nutr. 2009 May 18:1-7. [Epub ahead of print]
Diet influences the composition of the gut microbiota and host's health, particularly in patients suffering from food-related diseases. Coeliac disease (CD) is a permanent intolerance to cereal gluten proteins and the only therapy for the patients is to adhere to a life-long gluten-free diet (GFD). In the present preliminary study, the effects of a GFD on the composition and immune function of the gut microbiota were analysed in ten healthy subjects (mean age 30.3 years) over 1 month. Faecal microbiota was analysed by fluorescence in situ hybridisation (FISH) and quantitative PCR (qPCR). The ability of faecal bacteria to stimulate cytokine production by peripheral blood mononuclear cells (PBMC) was determined by ELISA. No significant differences in dietary intake were found before and after the GFD except for reductions (P = 0.001) in polysaccharides. Bifidobacterium, Clostridium lituseburense and Faecalibacterium prausnitzii proportions decreased (P = 0.007, P = 0.031 and P = 0.009, respectively) as a result of the GFD analysed by FISH. Bifidobacterium, Lactobacillus and Bifidobacterium longum counts decreased (P = 0.020, P = 0.001 and P = 0.017, respectively), while Enterobacteriaceae and Escherichia coli counts increased (P = 0.005 and P = 0.003) after the GFD assessed by qPCR. TNF-alpha, interferon-gamma, IL-10 and IL-8 production by PBMC stimulated with faecal samples was also reduced (P = 0.021, P = 0.037, P = 0.002 and P = 0.007, respectively) after the diet. Therefore, the GFD led to reductions in beneficial gut bacteria populations and the ability of faecal samples to stimulate the host's immunity. Thus, the GFD may constitute an environmental variable to be considered in treated CD patients for its possible effects on gut health.
2. Parent Ratings of Behavorial Effects of Biomedical Interventions
http://www.autism.com/treatable/form34qr.htm
3. Elevated immune response in the brain of autistic patients.
Li X et al. J Neuroimmunol. 2009 Feb 15;207(1-2):111-6.
This study determined immune activities in the brain of ASD patients and matched normal subjects by examining cytokines in the brain tissue. Our results showed that proinflammatory cytokines (TNF-alpha, IL-6 and GM-CSF), Th1 cytokine (IFN-gamma) and chemokine (IL-8) were significantly increased in the brains of ASD patients compared with the controls. However the Th2 cytokines (IL-4, IL-5 and IL-10) showed no significant difference. The Th1/Th2 ratio was also significantly increased in ASD patients. Conclusion: ASD patients displayed an increased innate and adaptive immune response through the Th1 pathway, suggesting that localized brain inflammation and autoimmune disorder may be involved in the pathogenesis of ASD.
4. Elevation of tumor necrosis factor-alpha in cerebrospinal fluid of autistic children.
Chez MG et al. Pediatr Neurol. 2007 Jun;36(6):361-5.
Recent reports implicating elevated cytokines in the central nervous system in a small number of patients studied with autism have reported clinical regression. These studies have not focused on tumor necrosis factor-alpha as a possible marker for inflammatory damage. A series of 10 children with autism had clinical evaluation of their serum and spinal fluid for inflammatory changes and possible metabolic disease as part of their neurological evaluation. Elevation of cerebrospinal fluid levels of tumor necrosis factor-alpha was significantly higher (mean = 104.10 pg/mL) than concurrent serum levels (mean = 2.78 pg/mL) in all of the patients studied. The ratio of the cerebrospinal fluid levels to serum levels averaged 53.7:1. This ratio is significantly higher than the elevations reported for other pathological states for which cerebrospinal fluid and serum tumor necrosis factor-alpha levels have been simultaneously measured. This observation may offer a unique insight into central nervous system inflammatory mechanisms that may contribute to the onset of autism and may serve as a potential clinical marker. More controlled study of this potentially important observation may prove valuable.
5. Immune activation of peripheral blood and mucosal CD3+ lymphocyte cytokine profiles in children with autism and gastrointestinal symptoms.
Ashwood P, Wakefield AJ. J Neuroimmunol. 2006 Apr;173(1-2):126-34.
Gastrointestinal pathology, characterized by lymphoid nodular hyperplasia and entero-colitis, has been demonstrated in a cohort of children with autistic spectrum disorder (ASD). Systemic and intestinal mucosal immune dysregulation was assessed in ASD children with gastrointestinal (GI) symptoms (n = 18), and typically developing controls (n = 27), including non-inflamed controls (NIC) and inflamed GI control children with Crohn's disease (CD), by analysis of intracellular cytokines in CD3+ lymphocytes. In both peripheral blood and mucosa, CD3+ TNFalpha+ and CD3+ IFNgamma+ were increased in ASD children compared with NIC (p < 0.004) and reached levels similar to CD. In contrast, peripheral and mucosal CD3+ IL-10+ were markedly lower in ASD children with GI symptoms compared with both NIC and CD controls (p < 0.02). In addition, mucosal CD3+ IL-4+ cells were increased (p < 0.007) in ASD compared with NIC. There is a unique pattern of peripheral blood and mucosal CD3+ lymphocytes intracellular cytokines, which is consistent with significant immune dysregulation, in this ASD cohort.
6. Cerebrospinal fluid and serum markers of inflammation in autism.
Zimmerman AW et al. Pediatr Neurol. 2005 Sep;33(3):195-201.
Systemic immune abnormalities have no known relevance to brain dysfunction in autism. In order to find evidence for neuroinflammation, we compared levels of sensitive indicators of immune activation: quinolinic acid, neopterin, and biopterin, as well as multiple cytokines and cytokine receptors, in cerebrospinal fluid and serum from children with autism, to control subjects with other neurologic disorders. In cerebrospinal fluid from 12 children with autism, quinolinic acid (P = 0.037) and neopterin (P = 0.003) were decreased, and biopterin (P = 0.040) was elevated, compared with control subjects. In sera from 35 persons with autism, among cytokines, only tumor necrosis factor receptor II was elevated compared with controls (P < 0.02). Decreased quinolinic acid and neopterin in cerebrospinal fluid are paradoxical and suggest dysmaturation of metabolic pathways and absence of concurrent infection, respectively, in autism. Alternatively, they may be produced by microglia but remain localized and not expressed in cerebrospinal fluid.
7. Evaluation of an association between gastrointestinal symptoms and cytokine production against common dietary proteins in children with autism spectrum disorders.
Jyonouchi H et al. J Pediatr. 2005 May;146(5):605-10.
OBJECTIVE: To evaluate an association between cytokine production with common dietary proteins as a marker of non-allergic food hypersensitivity (NFH) and gastrointestinal (GI) symptoms in young children with autism spectrum disorders (ASD). STUDY DESIGN: Peripheral blood mononuclear cells (PBMCs) were obtained from 109 ASD children with or without GI symptoms (GI [+] ASD, N = 75 and GI (-) ASD, N = 34], from children with NFH (N = 15), and control subjects (N = 19). Diarrhea and constipation were the major GI symptoms. We measured production of type 1 T-helper cells (Th1), type 2 T-helper cells (Th2), and regulatory cytokines by PBMCs stimulated with whole cow's milk protein (CMP), its major components (casein, beta-lactoglobulin, and alpha-lactoalbumin), gliadin, and soy. RESULTS: PBMCs obtained from GI (+) ASD children produced more tumor necrosis factor-alpha (TNF-alpha)/interleukin-12 (IL-12) than those obtained from control subjects with CMP, beta-lactoglobulin, and alpha-lactoalbumin, irrespective of objective GI symptoms. They also produced more TNF-alpha with gliadin, which was more frequently observed in the group with loose stools. PBMCs obtained from GI (-) ASD children produced more TNF-alpha/IL-12 with CMP than those from control subjects, but not with beta-lactoglobulin, alpha-lactoalbumin, or gliadin. Cytokine production with casein and soy were unremarkable. CONCLUSION: A high prevalence of elevated TNF-alpha/IL-12 production by GI (+) ASD PBMCs with CMP and its major components indicates a role of NFH in GI symptoms observed in children with ASD.
8. Dysregulated innate immune responses in young children with autism spectrum disorders: their relationship to gastrointestinal symptoms and dietary intervention.
Jyonouchi H et al. Neuropsychobiology. 2005;51(2):77-85.
OBJECTIVE: Our previous study indicated an association between cellular immune reactivity to common dietary proteins (DPs) and excessive proinflammatory cytokine production with endotoxin (lipopolysaccharide, LPS), a major stimulant of innate immunity in the gut mucosa, in a subset of autism spectrum disorder (ASD) children. However, it is unclear whether such abnormal LPS responses are intrinsic in these ASD children or the results of chronic gastrointestinal (GI) inflammation secondary to immune reactivity to DPs. This study further explored possible dysregulated production of proinflammatory and counter-regulatory cytokines with LPS in ASD children and its relationship to GI symptoms and the effects of dietary intervention measures. METHODS: This study includes ASD children (median age 4.8 years) on the unrestricted (n = 100) or elimination (n = 77) diet appropriate with their immune reactivity. Controls include children with non-allergic food hypersensitivity (NFH; median age 2.9 years) on the unrestricted (n = 14) or elimination (n = 16) diet, and typically developing children (median age 4.5 years, n = 13). The innate immune responses were assessed by measuring production of proinflammatory (TNF-alpha, IL-1beta, IL-6, and IL-12) and counter-regulatory (IL-1ra, IL-10, and sTNFRII) cytokines by peripheral blood mononuclear cells (PBMCs) with LPS. The results were also compared to T-cell responses with common DPs and control T-cell mitogens assessed by measuring T-cell cytokine production. RESULTS: ASD and NFH PBMCs produced higher levels of TNF-alpha with LPS than controls regardless of dietary interventions. However, only in PBMCs from ASD children with positive gastrointestinal (GI(+)) symptoms, did we find a positive association between TNF-alpha levels produced with LPS and those with cow's milk protein (CMP) and its major components regardless of dietary interventions. In the unrestricted diet group, GI(+) ASD PBMCs produced higher IL-12 than controls and less IL-10 than GI(-) ASD PBMCs with LPS. GI(+) ASD but not GI(-) ASD or NFH PBMCs produced less counter-regulatory cytokines with LPS in the unrestricted diet group than in the elimination diet group. There was no significant difference among the study groups with regard to cytokine production in responses to T-cell mitogens and other recall antigens. Conclusion: Our results revealed that there are findings limited to GI(+) ASD PBMCs in both the unrestricted and elimination diet groups. Thus our findings indicate intrinsic defects of innate immune responses in GI(+) ASD children but not in NFH or GI(-) ASD children, suggesting a possible link between GI and behavioral symptoms mediated by innate immune abnormalities.
9. Spontaneous mucosal lymphocyte cytokine profiles in children with autism and gastrointestinal symptoms: mucosal immune activation and reduced counter regulatory interleukin-10.
Ashwood P et al. J Clin Immunol. 2004 Nov;24(6):664-73.
A lymphocytic enterocolitis has been reported in a cohort of children with autistic spectrum disorder (ASD) and gastrointestinal (GI) symptoms. This study tested the hypothesis that dysregulated intestinal mucosal immunity with enhanced pro-inflammatory cytokine production is present in these ASD children. Comparison was made with developmentally normal children with, and without, mucosal inflammation. Duodenal and colonic biopsies were obtained from 21 ASD children, and 65 developmentally normal paediatric controls, of which 38 had signs of histological inflammation. Detection of CD3+ lymphocyte staining for spontaneous intracellular TNFalpha, IL-2, IL-4, IFNgamma, and IL-10, was performed by multicolor flow cytometry. Duodenal and colonic mucosal CD3+ lymphocyte counts were elevated in ASD children compared with noninflamed controls (p<0.03). In the duodenum, the proportion of lamina propria (LP) and epithelial CD3(+)TNFalpha+ cells in ASD children was significantly greater compared with noninflamed controls (p<0.002) but not coeliac disease controls. In addition, LP and epithelial CD3(+)IL-2+ and CD3(+)IFNgamma+, and epithelial CD3(+)IL-4+ cells were more numerous in ASD children than in noninflamed controls (p<0.04). In contrast, CD3(+)IL-10+ cells were fewer in ASD children than in noninflamed controls (p<0.05). In the colon, LP CD3(+)TNFalpha+ and CD3(+)IFNgamma+ were more frequent in ASD children than in noninflamed controls (p<0.01). In contrast with Crohn's disease and non-Crohn's colitis, LP and epithelial CD3(+)IL-10+ cells were fewer in ASD children than in nondisease controls (p<0.01). There was a significantly greater proportion of CD3(+)TNFalpha+ cells in colonic mucosa in those ASD children who had no dietary exclusion compared with those on a gluten and/or casein free diet (p<0.05). There is a consistent profile of CD3+ lymphocyte cytokines in the small and large intestinal mucosa of these ASD children, involving increased pro-inflammatory and decreased regulatory activities. The data provide further evidence of a diffuse mucosal immunopathology in some ASD children and the potential for benefit of dietary and immunomodulatory therapies.
10. High nitric oxide production in autistic disorder: a possible role for interferon-gamma.
Sweeten TL et al. Biol Psychiatry. 2004 Feb 15;55(4):434-7.
BACKGROUND: Neuroimmune regulation abnormalities have been implicated in the pathophysiology of autistic disorder. Nitric oxide (NO) is involved in immune reactivity and is known to affect brain neurodevelopmental processes. Recent evidence indicates that NO, and cytokines involved in NO production, may be high in children with autism. The purpose of this study was to verify that plasma NO is high in children with autism and determine whether this elevation is related to plasma levels of cytokines involved in NO production. METHODS: The metabolites of NO, nitrite, and nitrate (NOx), along with the cytokines interferon-gamma (IFN-gamma), tumor necrosis factor-alpha, and interleukin-1beta, were measured in plasma of 29 children with autism (mean age +/- SD = 6.1 +/- 2.8 years) and 27 age- and gender-matched healthy comparison subjects using commercially available assay kits. RESULTS: Plasma levels of NOx were significantly higher in the autistic subjects (p =.006); plasma levels of the cytokines did not differ between groups. NOx and IFN-gamma levels were positively correlated in the autistic subjects (r =.51; p =.005). CONCLUSIONS: These results confirm that plasma NO is high in some children with autism and suggest that this elevation may be related to IFN-gamma activity.
11. Innate immunity associated with inflammatory responses and cytokine production against common dietary proteins in patients with autism spectrum disorder.
Jyonouchi H, Sun S, Itokazu N. Neuropsychobiology. 2002;46(2):76-84.
OBJECTIVES: Children with autism spectrum disorder (ASD) frequently reveal various gastrointestinal (GI) symptoms that may resolve with an elimination diet along with apparent improvement of some of the behavioral symptoms. Evidence suggests that ASD may be accompanied by aberrant (inflammatory) innate immune responses. This may predispose ASD children to sensitization to common dietary proteins (DP), leading to GI inflammation and aggravation of some behavioral symptoms. METHODS: We measured IFN-gamma, IL-5, and TNF-alpha production against representative DPs [gliadin, cow's milk protein (CMP), and soy] by peripheral blood mononuclear cells (PBMCs) from ASD and control children [those with DP intolerance (DPI), ASD siblings, and healthy unrelated children]. We evaluated the results in association with proinflammatory and counter-regulatory cytokine production with endotoxin (LPS), a microbial product of intestinal flora and a surrogate stimulant for innate immune responses. RESULTS: ASD PBMCs produced elevated IFN-gamma and TNF-alpha, but not IL-5 with common DPs at high frequency as observed in DPI PBMCs. ASD PBMCs revealed increased proinflammatory cytokine responses with LPS at high frequency with positive correlation between proinflammatory cytokine production with LPS and IFN-gamma and TNF-alpha production against DPs. Such correlation was less evident in DPI PBMCs. CONCLUSION: Immune reactivity to DPs may be associated with apparent DPI and GI inflammation in ASD children that may be partly associated with aberrant innate immune response against endotoxin, a product of the gut bacteria.
12. Activation of the inflammatory response system in autism.
Croonenberghs J et al. Neuropsychobiology. 2002;45(1):1-6.
BACKGROUND/AIM: There is now some evidence that autism may be accompanied by abnormalities in the inflammatory response system (IRS). Products of the IRS, such as proinflammatory cytokines, may induce some of the behavioral symptoms of autism, such as social withdrawal, resistance to novelty and sleep disturbances. The main aim of the present study was to examine whether autism is accompanied by an activation of the IRS. METHODS: We measured the production of interleukin (IL)-6, IL-10, the IL-1 receptor antagonist (IL-1RA), interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha by whole blood and the serum concentrations of IL-6, the IL-2 receptor (IL-2R) and IL-1RA. RESULTS: This study showed a significantly increased production of IFN-gamma and IL-1RA and a trend toward a significantly increased production of IL-6 and TNF-alpha by whole blood of autistic children. There were no significant differences in the serum concentrations of IL-6, IL-2R and IL-1RA between autistic and normal children. CONCLUSIONS: These results suggest that autism may be accompanied by an activation of the monocytic (increased IL-1RA) and Th-1-like (increased IFN-gamma) arm of the IRS. It is hypothesized that increased production of proinflammatory cytokines could play a role in the pathophysiology of autism.
13. Proinflammatory and regulatory cytokine production associated with innate and adaptive immune responses in children with autism spectrum disorders and developmental regression.
Jyonouchi H, Sun S, Le H. J Neuroimmunol. 2001 Nov 1;120(1-2):170-9.
We determined innate and adaptive immune responses in children with developmental regression and autism spectrum disorders (ASD, N=71), developmentally normal siblings (N=23), and controls (N=17). With lipopolysaccharide (LPS), a stimulant for innate immunity, peripheral blood mononuclear cells (PBMCs) from 59/71 (83.1%) ASD patients produced >2 SD above the control mean (CM) values of TNF-alpha, IL-1beta, and/or IL-6 produced by control PBMCs. ASD PBMCs produced higher levels of proinflammatory/counter-regulatory cytokines without stimuli than controls. With stimulants of phytohemagglutinin (PHA), tetanus, IL-12p70, and IL-18, PBMCs from 47.9% to 60% of ASD patients produced >2 SD above the CM values of TNF-alpha depending on stimulants. Our results indicate excessive innate immune responses in a number of ASD children that may be most evident in TNF-alpha production.
14. An infection-based model of neurodevelopmental damage.
Hornig M et al. Proc Natl Acad Sci U S A. 1999 Oct 12;96(21):12102-7.
http://www.pnas.org/content/96/21/12102.long
Perinatal exposure to infectious agents and toxins is linked to the pathogenesis of neuropsychiatric disorders, but the mechanisms by which environmental triggers interact with developing immune and neural elements to create neurodevelopmental disturbances are poorly understood. We describe a model for investigating disorders of central nervous system development based on neonatal rat infection with Borna disease virus, a neurotropic noncytolytic RNA virus. Infection results in abnormal righting reflexes, hyperactivity, inhibition of open-field exploration, and stereotypic behaviors. Architecture is markedly disrupted in hippocampus and cerebellum, with reduction in granule and Purkinje cell numbers. Neurons are lost predominantly by apoptosis, as supported by increased mRNA levels for pro-apoptotic products (Fas, caspase-1), decreased mRNA levels for the anti-apoptotic bcl-x, and in situ labeling of fragmented DNA. Although inflammatory infiltrates are observed transiently in frontal cortex, glial activation (microgliosis > astrocytosis) is prominent throughout the brain and persists for several weeks in concert with increased levels of proinflammatory cytokine mRNAs (interleukins 1alpha, 1beta, and 6 and tumor necrosis factor alpha) and progressive hippocampal and cerebellar damage. The resemblance of these functional and neuropathologic abnormalities to human neurodevelopmental disorders suggests the utility of this model for defining cellular, biochemical, histologic, and functional outcomes of interactions of environmental influences with the developing central nervous system.
15. Preliminary evidence of the in vitro effects of BDE-47 on innate immune responses in children with autism spectrum disorders.
Ashwood P et al. J Neuroimmunol. 2009 Mar 31;208(1-2):130-5.
Autism spectrum disorders (ASD) are complex neurodevelopmental disorders that manifest in childhood. Immune dysregulation and autoimmune reactivity may contribute to the etiology of ASD and are likely the result of both genetic and environmental susceptibilities. A common environmental contaminant, 2,2',4,4'-tetrabrominated biphenyl (BDE-47), was tested for differential effects on the immune response of peripheral blood mononuclear cells (PBMC) isolated from children with ASD (n=19) and age-matched typically developing controls (TD, n=18). PBMC were exposed in vitro to either 100 nM or 500 nM BDE-47, before challenge with bacterial lipopolysaccharide (LPS), an innate immune activator, with resultant cytokine production measured using the Luminex multiplex platform. The cytokine responses of LPS stimulated PBMC from ASD and TD subjects diverged in the presence of 100 nM BDE. For example, cells cultured from the TD group demonstrated significantly decreased levels of the cytokines IL-12p40, GM-CSF, IL-6, TNFalpha, and the chemokines MIP-1alpha and MIP-1beta following LPS stimulation of PBMC pretreated with 100 nM BDE-47 compared with samples treated with vehicle control (p<0.05). In contrast, cells cultured from subjects with ASD demonstrated an increased IL-1beta response to LPS (p=0.033) when pretreated with 100 nM BDE-47 compared with vehicle control. Preincubation with 500 nM BDE-47 significantly increased the stimulated release of the inflammatory chemokine IL-8 (p<0.04) in cells cultured from subjects with ASD but not in cells from TD controls. These data suggest that in vitro exposure of PBMC to BDE-47 affects cell cytokine production in a pediatric population. Moreover, PBMC from the ASD subjects were differentially affected when compared with the TD controls suggesting a biological basis for altered sensitivity to BDE-47 in the ASD population.
16. Plasma increase of interleukin-12 and interferon-gamma. Pathological significance in autism.
Singh VK. J Neuroimmunol. 1996 May;66(1-2):143-5.
Immune factors such as autoimmunity have been implicated in the genesis of autism, a neurodevelopmental disorder. Since autoimmune response involves immune activation, the plasma levels of interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), interleukin-12 (IL-12), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and soluble intercellular adhesion molecule-1 (sICAM-1) were measured in autistic patients and age-matched normal controls. The levels of IL-12 and IFN-gamma were significantly (P < or = 0.05) higher in patients as compared to controls. However, IFN-alpha, IL-6, TNF-alpha, and sICAM-1 levels did not significantly differ between the two groups. Because macrophage-derived IL-12 is known to selectively induce IFN-gamma in T helper type-1 (Th-1) cells, it is suggested that IL-12 and IFN-gamma increases may indicate antigenic stimulation of Th-1 cells pathogenetically linked to autoimmunity in autism.
17. Microglial activation and TNFalpha production mediate altered CNS excitability following peripheral inflammation.
Riazi K et al. Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):17151-6.
http://www.pnas.org/content/105/44/17151.long
Peripheral inflammation leads to a number of centrally mediated physiological and behavioral changes. The underlying mechanisms and the signaling pathways involved in these phenomena are not yet well understood. We hypothesized that peripheral inflammation leads to increased neuronal excitability arising from a CNS immune response. We induced inflammation in the gut by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) to adult male rats. To examine the excitability of the brain in vivo, we administered pentylenetetrazole (PTZ; a GABAergic antagonist) intravenously to evoke clonic seizures. Rats treated with TNBS showed increased susceptibility to PTZ seizures that was strongly correlated with the severity and progression of intestinal inflammation. In vitro hippocampal slices from inflamed, TNBS-treated rats showed increased spontaneous interictal burst firing following application of 4-aminopyridine, indicating increased intrinsic excitability. The TNBS-treated rats exhibited a marked, reversible inflammatory response within the hippocampus, characterized by microglial activation and increases in tumor necrosis factor alpha (TNFalpha) levels. Central antagonism of TNFalpha using a monoclonal antibody or inhibition of microglial activation by i.c.v. injection of minocycline prevented the increase in seizure susceptibility. Moreover, i.c.v. infusion of TNFalpha in untreated rats for 4 days also increased seizure susceptibility and thus mimicked the changes in seizure threshold observed with intestinal inflammation. Our finding of a microglia-dependent TNFalpha-mediated increase in CNS excitability provides insight into potential mechanisms underlying the disparate neurological and behavioral changes associated with chronic inflammation.
18. Gliadin stimulates human monocytes to production of IL-8 and TNF-alpha through a mechanism involving NF-kappaB.
Jelínková L et al. FEBS Lett. 2004 Jul 30;571(1-3):81-5.
Wheat gliadin is the triggering agent in coeliac disease. In this study, we documented that proteolytic fragments of gliadin, in contrast to other food antigens, induced interleukin (IL)-8 and tumour necrosis factor-alpha (TNF-alpha) production and significantly increased interferon (IFN)-gamma-induced cytokine secretion in human monocytic line THP-1 cells. Stimulation with gliadin resulted in elevated phosphorylation of the IkappaBalpha molecule and increased NF-kappaB/DNA binding activity that was inhibited by sulfasalazine, l-1-tosylamido-2-phenylethyl chloromethyl ketone and pyrrolidine dithiocarbamate (PDTC). The activation pathway was shown to be independent of the CD14 molecule. Less mature U-937 monocytes responded to gliadin stimulation by low IL-8 secretion, TNF-alpha production was not detectable. We propose that gliadin-induced activation of monocytes/macrophages can participate in mechanisms leading to the impairment of intestinal mucosa in coeliac patients.
19. Inflammatory cytokines in small intestinal mucosa of patients with potential coeliac disease.
Westerholm-Ormio M et al. Clin Exp Immunol. 2002 Apr;128(1):94-101.
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1906370&blobtype=pdf
T helper cell type 1 (Th1) response to gluten has been implicated in the pathogenesis of coeliac disease (CD). To characterize immunological activation and mild inflammations leading to overt CD in potential coeliac patients, jejunal biopsies were obtained from family members of patients with CD or dermatitis herpetiformis (DH). Nine family members and one latent CD, eight CD patients and eight normal controls furnished jejunal biopsy specimens. Immunohistochemical staining of sections for interleukin-1alpha (IL-1alpha), IL-2, IL-4, interferon-gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha), CD3, gammadelta-T cell receptor (gammadelta-TCR), and alphabeta-TCR was carried out with monoclonal antibodies. Further, expression of IL-4 and IFN-gamma messenger RNA was detected by radioactive in situ hybridization in these same samples. In lamina propria, CD patients and potential CD patients had higher densities of IL-2 (P = 0.028, P = 0.043), IL-4 (P = 0.021, P = 0.034) and IFN-gamma positive cells (P = 0.000, P = 0.009) than did controls. Moreover, CD patients showed a higher density of TNF-alpha positive cells (P = 0.012, P = 0.001) than the other two groups, and expression of IFN-gamma mRNA (P = 0.035) was higher in them than in the other two study groups. Additionally, higher densities of TNF-alpha and IFN-gamma positive cells occurred in potential CD patients with high gammadelta-TCR+ intraepithelial lymphocytes (IELs). Our findings support the hypothesis that lamina propria T cells and macrophages, through their secretion of cytokines, play a central role in the pathogenesis of coeliac disease. The inflammatory cytokines found in potential CD specimens strongly suggest that these inflammatory markers can be identified long before visible villous changes have occurred.
20. Activation of macrophages by food antigens: enhancing effect of gluten on nitric oxide and cytokine production.
Tucková L et al. J Leukoc Biol. 2000 Mar;67(3):312-8.
http://www.jleukbio.org/cgi/reprint/67/3/312
Macrophages play an important role in effector mechanisms of various chronic inflammatory diseases. We studied the effect of gluten, the agent inducing celiac disease, and other food antigens on the activation of macrophages. Nitric oxide (NO) and cytokine production were followed as markers of activation, using cultured murine peritoneal macrophages. None of the food antigens tested caused direct inducible nitric oxide synthase (iNOS) activation in macrophages. Unlike other food antigens gluten, gliadin, and their proteolytic fragments significantly enhanced NO production when applied together with interferon-gamma (IFN-gamma), the most efficient being fragments originating from 25- to 45-min peptic digestion. The activation pathway was mediated via direct stimulation of tumor necrosis factor alpha (TNF-alpha) secretion. The NO-enhancing effect was confirmed at the level of iNOS mRNA transcription. In case of sustained local inflammatory reaction connected with increase of IFN-gamma, gluten and its proteolytic fragments may thus elevate NO production. Increased NO level could consequently participate in the development of mucosal lesions in the gut of celiac patients.
22. Clinical and pathological spectrum of coeliac disease--active, silent, latent, potential.
Ferguson A et al. Gut. 1993 Feb;34(2):150-1.
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1373959&blobtype=pdf
22. Celiac disease and the spectrum of gluten sensitivity.
Frick TJ, Olsen WA. Gastroenterologist. 1994 Dec;2(4):285-92.
Celiac disease is a well-known entity in which intolerance to wheat gluten and related proteins from barley, rye, and oats (collectively known as prolamins) damage intestinal mucosa. New insights into the pathology of the celiac intestinal lesion point to a wider spectrum of gluten sensitivity than previously thought. Recent advances in immunology and genetics have shed light on the underlying mechanisms and risks associated with the disease. Although the classical manifestations are well known, the wide variety of clinical presentations make celiac disease often difficult to diagnose, and the ubiquitous presence of prolamins in the Western diet make treatment challenging.
23. The spectrum of coeliac disease in children.
Catassi C, Fabiani E. Baillieres Clin Gastroenterol. 1997 Sep;11(3):485-507.
Coeliac disease is the life-long intolerance to dietary gluten, usually characterized by severe damage to the small-intestinal mucosa. The widespread use of sensitive diagnostic tools, such as the serum anti-gliadin and the anti-endomysial antibodies, has shown not only that coeliac disease is one of the commonest disorders in Western countries but also that this condition is characterized by a higher degree of clinical variability than previously thought (typical, atypical and silent forms). The existence of a latent-potential coeliac disease and even a gluten-sensitive disease with immunological activation of an otherwise normal small-intestinal mucosa has recently been postulated. An increased prevalence of coeliac disease in a number of other disorders has also been reported in both children and adults. The reasons for such a wide clinical heterogeneity are still poorly understood but are likely to depend on both genetic and environmental factors. Further investigations are required to evaluate the impact of undiagnosed, clinically milder forms of coeliac disease on the well-being of the population.
24. The widening spectrum of celiac disease.
Murray JA. Am J Clin Nutr. 1999 Mar;69(3):354-65.
http://www.ajcn.org/cgi/content/full/69/3/354
Celiac disease is a permanent intolerance to ingested gluten that results in immunologically mediated inflammatory damage to the small-intestinal mucosa. Celiac disease is associated with both human leukocyte antigen (HLA) and non-HLA genes and with other immune disorders, notably juvenile diabetes and thyroid disease. The classic sprue syndrome of steatorrhea and malnutrition coupled with multiple deficiency states may be less common than more subtle and often monosymptomatic presentations of the disease. Diverse problems such as dental anomalies, short stature, osteopenic bone disease, lactose intolerance, infertility, and nonspecific abdominal pain among many others may be the only manifestations of celiac disease. The rate at which celiac disease is diagnosed depends on the level of suspicion for the disease. Although diagnosis relies on intestinal biopsy findings, serologic tests are useful as screening tools and as an adjunct to diagnosis. The treatment of celiac disease is lifelong avoidance of dietary gluten. Gluten-free diets are now readily achievable with appropriate professional instruction and community support. Both benign and malignant complications of celiac disease occur but these can often be avoided by early diagnosis and compliance with a gluten-free diet.
25. Current approaches to diagnosis and treatment of celiac disease: an evolving spectrum.
Fasano A, Catassi C. Gastroenterology. 2001 Feb;120(3):636-51.
Celiac disease (CD) is a syndrome characterized by damage of the small intestinal mucosa caused by the gliadin fraction of wheat gluten and similar alcohol-soluble proteins (prolamines) of barley and rye in genetically susceptible subjects. The presence of gluten in these subjects leads to self-perpetuating mucosal damage, whereas elimination of gluten results in full mucosal recovery. The clinical manifestations of CD are protean in nature and vary markedly with the age of the patient, the duration and extent of disease, and the presence of extraintestinal pathologic conditions. In addition to the classical gastrointestinal form, a variety of other clinical manifestations of the disease have been described, including atypical and asymptomatic forms. Therefore, diagnosis of CD is extremely challenging and relies on a sensitive and specific algorithm that allows the identification of different manifestations of the disease. Serologic tests developed in the last decade provide a noninvasive tool to screen both individuals at risk for the disease and the general population. However, the current gold standard for the diagnosis of CD remains histologic confirmation of the intestinal damage in serologically positive individuals. The keystone treatment of CD patients is a lifelong elimination diet in which food products containing gluten are avoided.
26. Range of neurologic disorders in patients with celiac disease.
Zelnik N et al. Pediatr Neurol. 2008 Dec;39(6):392-8.
OBJECTIVE: During the past 2 decades, celiac disease (CD) has been recognized as a multisystem autoimmune disorder. A growing body of distinct neurologic conditions such as cerebellar ataxia, epilepsy, myoclonic ataxia, chronic neuropathies, and dementia have been reported, mainly in middle-aged adults. There still are insufficient data on the association of CD with various neurologic disorders in children, adolescents, and young adults, including more common and "soft" neurologic conditions, such as headache, learning disorders, attention-deficit/hyperactivity disorder (ADHD), and tic disorders. The aim of the present study is to look for a broader spectrum of neurologic disorders in CD patients, most of them children or young adults. METHODS: Patients with CD were asked to fill in a questionnaire regarding the presence of neurologic disorders or symptoms. Their medical charts were reviewed, and those who were reported as having neurologic manifestations underwent neurologic examination and brain imaging or electroencephalogram if required. Their neurologic data were compared with that of a control group matched for age and gender. RESULTS: Patients with CD were more prone to develop neurologic disorders (51.4%) in comparison with control subjects (19.9%). These disorders include hypotonia, developmental delay, learning disorders and ADHD, headache, and cerebellar ataxia. Epileptic disorders were only marginally more common in CD. In contrast, no difference was found in the prevalence of tic disorders in both groups. Therapeutic benefit, with gluten-free diet, was demonstrated only in patients with transient infantile hypotonia and migraine headache. CONCLUSION: This study suggests that the variability of neurologic disorders that occur in CD is broader than previously reported and includes "softer" and more common neurologic disorders, such as chronic headache, developmental delay, hypotonia, and learning disorders or ADHD. Future longitudinal prospective studies might better define the full range of these neurologic disorders and their clinical response to a gluten-free diet.
27. Plasma cytokine profiles in patients with celiac disease and selective IgA deficiency.
Cataldo F et al. Pediatr Allergy Immunol. 2003 Aug;14(4):320-4.
Celiac disease (CD) and selective IgA deficiency (IgAD) are frequently associated, and share the same genetic background. The aim of the present study was to evaluate both Type 1 and 2 plasma cytokine levels in CD and in CD-IgAD. IL-2, TNF-alpha, IL-10, IL-4 and IL-13 plasma levels were measured both at diagnosis and after a gluten-free diet (GFD) in 32 CD patients, in 27 CD-IgAD patients and in 30 healthy controls. IFN-gamma levels were significantly higher in CD and CD-IgAD than in controls, TNF-alpha displayed significantly higher levels in CD-IgAD when compared both with controls and with CD, and IL-2 was in CD-IgAD significantly increased respect to controls. Kinetics of the Type 1 cytokine plasma levels did not show a clear relationship with the GFD in both groups of CD patients, and particularly in those with IgAD. IL-4 and IL-13, both at diagnosis and after a GFD, were not significantly different in controls and in celiac patients (with and without IgAD). IL-10, whose production is stimulated by the TNF-alpha, had significantly higher plasma levels in CD-IgAD, but not in CD patients, with a significant decrease after a GFD. CD and especially CD-IgAD patients display persistently higher pro-inflammatory cytokine levels, suggesting a persistent state of activation of pro-phlogistic signals in CD, particularly when IgAD coexists. Serial measurement of serum IL-10 may be an adjunctive evaluating criterion in the follow-up of CD-IgAD patients.
28. Gastrointestinal symptoms in children with an autism spectrum disorder and language regression.
Valicenti-McDermott MD et al. Pediatr Neurol. 2008 Dec;39(6):392-8.
Few studies have compared gastrointestinal problems in children with an autism spectrum disorder with and without a history of language regression. A cross-sectional study was conducted with structured interviews in 100 children with autism spectrum disorder, using a gastrointestinal questionnaire and a familial autoimmune questionnaire. By parental report, children with language regression more frequently exhibited an abnormal stool pattern (40% vs 12%, P = 0.006) and had an increased family history of celiac disease or inflammatory bowel disease (24% vs 0%, P = 0.001) and of rheumatoid arthritis (30% vs 11%, P = 0.03). Among 35 children with a family history of autoimmune disease, an abnormal stool pattern was reported more frequently in those with language regression (78% vs 15%, P = 0.001) than in those without. An association was observed between children with language regression, a family history of autoimmune disease, and gastrointestinal symptoms. Additional studies are needed to examine a possible shared autoimmune process.
29. The significance of ileo-colonic lymphoid nodular hyperplasia in children with autistic spectrum disorder.
Wakefield AJ et al. Eur J Gastroenterol Hepatol. 2005 Aug;17(8):827-36.
BACKGROUND: Intestinal mucosal pathology, characterized by ileo-colonic lymphoid nodular hyperplasia (LNH) and mild acute and chronic inflammation of the colorectum, small bowel and stomach, has been reported in children with autistic spectrum disorder (ASD). AIM: To assess ileo-colonic LNH in ASD and control children and to test the hypothesis that there is an association between ileo-colonic LNH and ASD in children. PATIENTS AND METHODS: One hundred and forty-eight consecutive children with ASD (median age 6 years; range 2-16; 127 male) with gastrointestinal symptoms were investigated by ileo-colonoscopy. Macroscopic and histological features were scored and compared with 30 developmentally normal (non-inflammatory bowel disease, non-coeliac disease) controls (median age 7 years; range 1-11; 25 male) showing mild non-specific colitis in 16 cases (13 male) and normal colonic histology in 14 cases (12 male). Seventy-four ASD children and 23 controls also underwent upper gastrointestinal endoscopy. The influence on ileal LNH of dietary restriction, age at colonoscopy, and co-existent LNH elsewhere in the intestine, was examined. RESULTS: The prevalence of LNH was significantly greater in ASD children compared with controls in the ileum (129/144 (90%) vs. 8/27 (30%), P < 0.0001) and colon (88/148 (59%) vs. 7/30 (23%), P = 0.0003), whether or not controls had co-existent colonic inflammation. The severity of ileal LNH was significantly greater in ASD children compared with controls, with moderate to severe ileal LNH present in 98 of 144 (68%) ASD children versus 4 of 27 (15%) controls (P < 0.0001). Severe ileal LNH was associated with co-existent colonic LNH in ASD children (P = 0.01). The presence and severity of ileal LNH was not influenced by either diet or age at colonoscopy (P = 0.2). Isolated ileal LNH without evidence of pathology elsewhere in the intestine was a rare event, occurring in less than 3% of children overall. On histopathological examination, hyperplastic lymphoid follicles are significantly more prevalent in the ileum of ASD children (84/138; 61%) compared with controls (2/23; 9%, P = 0.0001). CONCLUSION: Ileo-colonic LNH is a characteristic pathological finding in children with ASD and gastrointestinal symptoms, and is associated with mucosal inflammation. Differences in age at colonoscopy and diet do not account for these changes. The data support the hypothesis that LNH is a significant pathological finding in ASD children.
30. Intestinal lymphocyte populations in children with regressive autism: evidence for extensive mucosal immunopathology.
Ashwood P et al. J Clin Immunol. 2003 Nov;23(6):504-17.
Inflammatory intestinal pathology has been reported in children with regressive autism (affected children). Detailed analysis of intestinal biopsies in these children indicates a novel lymphocytic enterocolitis with autoimmune features; however, links with cognitive function remain unclear. To characterize further, the nature and extent of this disease we examined the mucosal infiltrate using flow cytometry. Duodenal, ileal, and colonic biopsies were obtained from 52 affected children, 25 histologically normal, and 54 histologically inflamed, developmentally normal controls. Epithelial and lamina propria lymphocyte populations were isolated and examined by multicolor flow cytometry. Adjacent biopsies were assessed by semiquantitative histopathology. At all sites, CD3(+) and CD3(+)CD8(+) IEL as well as CD3(+) LPL were significantly increased in affected children compared with developmentally normal noninflamed control groups (p<0.01) reaching levels similar to inflamed controls. In addition, two populations -- CD3(+)CD4(+) IEL and LP CD19(+) B cells -- were significantly increased in affected children compared with both noninflamed and inflamed control groups including IBD, at all sites examined (p<0.01). Histologically there was a prominent mucosal eosinophil infiltrate in affected children that was significantly lower in those on a gluten- and casein-free diet, although lymphocyte populations were not influenced by diet. The data provide further evidence of a pan-enteric mucosal immunopathology in children with regressive autism that is apparently distinct from other inflammatory bowel diseases.
31. Defective tumour necrosis factor-alpha production in mother's milk is related to cow's milk allergy in suckling infants.
Järvinen KM et al. Clin Exp Allergy. 2000 May;30(5):637-43.
BACKGROUND: The precise role of leucocytes in human milk is still unresolved. OBJECTIVE: To assist in clarifying the immune mechanisms involved in the development of CMA in suckling infants, we studied the role of immunoregulatory leucocytes and their mediators in human breast milk. METHODS: The study population consisted of 43 lactating mothers and their infants, aged 0.25-8.0 months, followed-up prospectively from birth. Of these mothers, 27 had an infant with challenge-proven cow's milk allergy manifested with either skin (n = 23), gastrointestinal (n = 2) or skin and gastrointestinal symptoms (n = 3). Sixteen mothers with a healthy infant served as controls. We evaluated the spontaneous and mitogen-induced tumour necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) production of human milk leucocytes and isolated peripheral blood lymphocytes in vitro with a commercial ELISA kit. RESULTS: TNFalpha production of breast milk leucocytes was significantly lower in the mothers with a cow's milk-allergic infant, whereas IFNgamma production of these cells was comparable in the two groups. CONCLUSION: Our results suggest that in the breast milk of mothers having an infant with cow's milk allergy, the number and function of TNFalpha-producing cells is defective. This might lead to a disturbance in the development of oral tolerance and thereby to the development of CMA in suckling infants. These novel results may help in clarifying the etiopathogenesis of CMA.
32. Cow's milk stimulated lymphocyte proliferation and TNFalpha secretion in hypersensitivity to cow's milk protein.
Motrich RD et al. Clin Immunol. 2003 Nov;109(2):203-11.
Although there is no reliable single laboratory test available for the diagnosis of cow's milk allergy, if an allergic mechanism is suspected, a number of laboratory studies may be useful in delineating specific proteins responsible for these disorders. In the current study we analyzed in vitro lymphocyte proliferation assays, specific secretion of TNFalpha in supernatant cultures and specific IgE, IgG, and IgA in a group of patients with hypersensitivity to cow's milk antigens. The stimulation index against a cow's milk antigen mixture, alpha-lactalbumin, beta-lactoglobulin, and casein was significant higher in the group of patients maintained on cow's milk-free diet for less than 4 months compared with the values observed in the control group and in the group of patients without a close contact to cow's milk proteins. A significant increase in TNF-alpha secretion was observed in supernatants from patients with close contact to cow's milk (CM). Specific IgE was detected in 59.3% of the patients, with higher specific IgE levels in patients who were not positive for the proliferation assay, suggesting a clear difference in the two mechanisms proposed as effectors in this disease. No differences in specific IgG and IgA levels were observed between the patient group and the control group, with a great dispersion among individuals in all groups tested. We conclude that a combination of the assays tested in this study, such as proliferative assay of peripheral blood mononuclear cells to CM, the quantitation of TNFalpha in culture supernatants, and serum specific IgE determination, are useful laboratory tests to identify cow's milk allergy among patients with immediate and non immediate adverse reactions, reducing the need for food allergen challenges in young children.
33. Fetal sensitization to cow's milk protein and wheat: cow's milk protein and wheat-specific TNF-alpha production by umbilical cord blood cells and subsequent decline of TNF-alpha production by peripheral blood mononuclear cells following dietary intervention.
Ward CM, Geng L, Jyonouchi H. Pediatr Allergy Immunol. 2007 Jun;18(4):276-80.
We present a case of fetal sensitization to cow's milk protein (CMP) and wheat, resulting in non-IgE mediated food allergy (NFA). Fetal sensitization was indicated by onset of NFA symptoms shortly after birth and CMP/wheat-specific tumor necrosis factor-alpha (TNF-alpha) production by cord blood mononuclear cells. Following dietary intervention, we observed a decline of TNF-alpha production by peripheral blood mononuclear cells with stimuli of these dietary proteins (DPs) but recurrence of reactivity was observed following viral gastroenteritis, while interleukin-10 production with these DPs persisted during his first 5 yr of life. This finding may indicate active suppressive mechanisms for maintaining oral tolerance.
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